Monday, December 27, 2004

Intelligent Design theory continues to pop up as an issue. Jim Lindgren of the Volokh Conspiracy points to a post on the topic:

How science works is by putting forth theories that are disprovable, not ones that are provable. When all other theories have been disproven, those still standing are the ones adopted by most scientists. ID is not a scientific theory, because it fails the test of being disprovable (or to be more precise, non-falsifiable), right out of the box. If Hugh [Hewitt] doesn't believe this, then let him postulate an experiment that one could perform, even in thought, that would show it to be false. ID simply says, "I'm not smart enough to figure out how this structure could evolve, therefore there must have been a designer." That's not science--it's simply an invocation of a deus ex machina, whether its proponents are willing to admit it or not. And it doesn't belong in a science classroom, except as an example of what's not science.

I invite Dennis Prager to attempt the same sort of thought experiment.

This is one of those things about science that a log of people just don't get. Science does not work by proving theories true. Rather, it works by attempting to disprove theories, and those theories that survive the process are provisionally true.

Another point about science is that theories derive their power from what they don't predict far more than what they do.

Newton's theory of gravity, called Newton's Law of Universal Gravitation, was an incredibly successful theory. It not only accounted for [most of] the motions of the planets in the solar system, it accurately predicted such things as the return of Halley's comet and the existence of the planet Neptune.

Newton's theory was considered vindicated when Halley's comet returned, pretty much when Halley said it would, and on the exact orbit he predicted it would.

Halley died before the return of the comet that bears his name, but there were many other comets that came through before Halley died. Why not claim one of those as vindication? Because Newton's theory did not predict that a comet would show up somewhere in the sky someday. It predicted that a comet would be seen coming in from a particular direction, and it would be following a particular path, and it would return in a particular time window.

It did.

Newton's theory predicted a great number of things, and accounted for most of the observed motions in the solar system. But there were any number of motions that were specifically ruled out. The theory predicted that planets would move in elliptical orbits, or circular orbits, or the occasional parabola or hyperbola. You would never expect to see a planet move on a sine wave through the solar system, or trace a cubic function or a catenary, or any of an infinite number of other possible curves, and making sharp turns is right out.

Had any of these movements been observed, Newton's theory would have been in deep trouble.

In contrast, we could imagine someone offering, as a counter to Newton's theory, the Intelligent Pilot Theory of Motion (IPTOM). In this theory, all the movements of all the planets, asteroids, comets, and dust particles in the solar system are due to the influence of an Intelligent Pilot. Every movement can be accounted for by claiming that it is what the Pilot willed.

The problem with the IPTOM is that if any movement can be accounted for by the theory, none can be ruled out, and there's no particular reason to expect any object, like a space craft, to behave in any particular way.

Take, for example, the topic of this post on gravity. We count on being able to predict the location of anything we launch into space with a high degree of accuracy decades into the future. A discrepency of a tiny fraction in one is a definite anomaly, a similar discrepency in two matching probes is downright weird.

But this discrepency is troubling only because Newton's theory makes very specific predictions about what can happen, and what can't happen.

One thing that strikes me about Intelligent Design is that it must have been much more intuitively appealing before the failure of socialism. Socialism in the 1920s--1940s was in part based on the idea that the world had become so complex that central planning was necessary to deal with this complexity. Yet Von Mises was arguing just the opposite, that as the world became more elaborate, no one could plan it. ID seems to be based on an assumption that most conservatives reject in the economic sphere--that as the economy gets more elaborate, to work well it must be the product of the intelligent design of a master planner.

Indeed, many conservatives are quite aware of the notion of spontaneous order in economic systems, but are completely unable to accept the same notion in biological systems. Modern Liberals are quite the opposite. They're perfectly comfortable with the notion of spontaneous order in nature – evolution – but refuse to believe that an economy can self-organize without an intelligence directing it.

Indeed, I have proposed this as one of the tests for distinguishing between Left and Right in American politics.